1. Field of the Invention
The present invention relates to a magneto-optic recording medium reproduction device, and more specifically to that employs near-field light and domain expansion.
2. Description of the Background Art
Magneto-optic recording medium has been noted as a highly reliable recording medium with rewritability and high storage capacity and has been put to practical use as the memory for computer and the like. However, further high density recording and reproducing technique has been sought for as the amount of information is further increased and the device is further miniaturized.
High density recording and reproducing technique is constituted by medium technique and device technique. The former technique includes a narrowed pitch of medium, an improved resolution for reproduction by means of magnetic multilayered film, and the like. The technique by means of magnetic multilayered film employs the fact that the intensity of laser spot forms Gaussian distribution to selectively transfer the magnetized state of a recording layer to a reproducing layer and read the magnetized state of the reproducing layer, and at present mainly has the three types of FAD (Front Aperture Detection), RAD (Rear Aperture Detection) and CAD (Center Aperture Detection). According to these techniques, the front or rear side or the vicinity of the center of a laser spot serves as a reproduction aperture to reduce the substantial diameter of a laser spot and thus increase reproduction density. The latter technique includes optical super-resolution technique for obtaining a condensation spot which exceeds the diffraction limit of laser beam, reduction in wavelength of laser beam and the like. Furthermore, near-field light recording and reproducing technique is provided for positioning one end surface of an optical fiber adjacent to a magneto-optic recording medium and irradiating the magneto-optic recording medium with laser beam from the optical fiber to record and reproduce signals. This technique allows formation of a recording domain of approximately 0.06 .mu.m.
For reproduction by near-field light recording and producing technique, however, the reproduced signals which are detected are small due to the small domain, sufficient C/N ratio cannot be obtained, and reproduced signals are disadvantageously lost.